1. Field of the Invention
The present invention relates to a suspender for fabricating single-crystal semiconductors, and more specifically, to a suspender for suspending a polycrystalline material in a chamber of crystal growing apparatus for feeding the crucible with the polycrystalline material as a raw material in fabrication of the single-crystal semiconductors.
2. Description of Prior Art
Single-crystal silicon is utilized as a substrate material for a semiconductor device. One well known method for fabricating single-crystal silicon, the Czochralski (CZ) method, involves pulling a cylindrical single-crystal silicon rod from melted material (melt) in a crucible. In the CZ method, the polysilicon material is charged into the crucible and is melted by a heater around the crucible. A single-crystal seed, which is fixed on a seed holder, is immersed in the melt. When the seed holder rises from the melt and rotates in the same direction or in the opposite direction as the rotation direction of the crucible, the single-crystal silicon rod is formed on the seed.
In recent years, as the diameter of the semiconductor wafer has increased, wafers with diameters of more than six inches have been widely utilized and are becoming well known in the semiconductor industry. Accordingly, the dimensions of the crystal growing apparatus for fabricating the single-crystal silicon must be expanded, and the amount of the single-crystal products increased. However, as the crystal growing apparatus is enlarged and the amount increased, the time required to produce the single-crystal has also increased. Moreover, after the removal of the single-crystal product from the chamber, the fabricating suspender, the crucible and the heaters require a longer cooling time to attain a temperature suitable for cleaning. Therefore, the manufacturing efficiency of the single-crystal silicon is affected.
In order to prevent any diminution of manufacturing efficiency, a recharge method has been provided. The recharge method charges polycrystalline material into the crucible repeatedly after the single-crystal silicon has been pulled. Therefore, the single-crystal manufacturing process can be repeated to avoid the frequent cooling and cleaning tasks of the furnace, thus increasing efficiency. On the other hand, several single-crystal rods instead of only one can be pulled from one crucible to reduce manufacturing costs. Moreover, in order to pull a long single-crystal rod with a large diameter from the crucible, supplementary polycrystalline material should be charged in the melt after the initially charged material has been melted and the rod is about to be pulled. That is, an additionally charged method should be utilized.
The polycrystalline material utilized in the recharge method or the additionally charged method are polycrystalline rods. Each of the polycrystalline rods, as illustrated in FIG. 8, has a body 2 on top of which a ring-shaped groove 2b and two small openings 2c are formed. Referring to FIG. 9, each polycrystalline rod is suspended on an arm 4a of suspending means 4 by a tantalum wire fixed on ring-shaped groove 2b through openings 2c. When suspending means 4 is lowered slowly, the polycrystalline rods will be melted by main heaters around the crucible or by sub-heaters and main heaters over the crucible, thereby providing the melt in the crucible.
However, several problems exist in the aforementioned suspender for suspending the polycrystalline rods. The problems include:
1. The polycrystalline rods require further tasks to form the ring-shaped grooves and the openings, thus increasing the manufacturing cost; PA1 2. In order to suspend the polycrystalline rods on the suspending means, wires (such as tantalum wires) must be utilized, thus further increasing the cost; PA1 3. More tasks and time are required to fasten the polycrystalline rods on the suspending means by the wires; PA1 4. The polycrystalline rods may be contaminated by the wires; and PA1 5. The polycrystalline rods may drop into the crucible if the wires break or are not properly fixed on the polycrystalline rods.